Process-of making



F. l. 4DU PONT.

PROCESS 0F MAKINGSIVIOI-(ELESS POWDER.

APPLICATION FILED MAH, 1915.

mmmlm Patented July l, 1919i.

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lillv FRANCIS I. DU PONT, OF WILMINGTON, DELAWARE, .ASSIGNOBABY DIRECTAND MESNE ASSIGNMENTS, TO BALL. GRAIN EXPLOSIVES COMPANY, OF WILMINGTON,DELA- WLRE, A CORPORATION OF DELAWARE.

PROCESS OF IVIAKINGSMOKELESS POWDER.

Specification of Letters Patent.

Patented July 1,1919.

applieation'fued May a, 1916. l serial no. 94,946.

To all whom t may concern.'

Be it known that I, FRANGIs ll. DU PONT,

a citizen of the United States, residing at.

Wilmington, county of New Castle, and State of Delaware, have invented anew and useful Improvement in Processes ofj Making Sme eless Powder,of'which the following is a full, clear, and exact description,reference being had to the accompanying drawings, which vform a -partofthis specification.

ln'the manufacture of smokeless powder it is well known to partly removethe water 'from the nitrocellulose by wringing in a centrifugal machine,then displacethe remaining water with alcohol by percolation withypressure to form #a cake containing from 20- to 25 per cent. alcohol,then breaking up the same, and then mixing with the alcoholizednitrocellulose ether in amount equal to about twice the amount ofalcohol,-

,then alcohol, and later with the alcohol.

This reversal of. the old processY possesses a great advantage in thatthe excess of ether can be removed with but aV small fraction ofthepressure required to remove the,

excess of alcohol in the old process. It is also associated with othernovel steps,where by the 'above results are secured and whereby also thevolume of ether to a given Weight of nitrocellulose may be accuratelypredetermined.

'lo carry out my invention l have provided a novel apparatus, anunderstanding of the construction and operation of which will enable theessential features of the process to 'be more readily comprehended. Inthe drawings: y

Figure l is a side elevation, lpartly in section, o'f the major part ofthe apparatus. Fig. 2 is a similar view, somewhat diagrammatic, of themixing machine. Fig.

' 3 is a side view of the hopper. Fig. 4c is an end view of the drier.Fig. 5 is a gitudinal section of the drier.

The nitrocellulose is wrung in a cent-rifuv gal machine (not shown), asheretofore, to expel as much of the water as is practicable. say untilit contains about 25 per cent. mois-l ture. rlhe nitrocellulose isthentransferred to a hopper a, having its bottom closed by an endlesscarrier b, which, with the roller c, transfers the nitrocellulose' in aslow and measured stream from the hopper to the drier.

The drier is essentially a long stationary cylinderl ai through the axisof which extends a rotary power driven shaft c having spokes f to whichare secured a worm g extendingclose to the inner wall of the cylpartiallon- -inder. rlFhe cylinder is supported on a frame work it irlclosing aheated cham'ber through which extend heating pipes e'. Warm air may alsobe introduced into the discharge end of the cylinder through the pipe cland caused to circulate through the same in the opposite direction tothat of the travel of the nitrocellulose. rl`he wall of the cylinder ismade of very thin sheet metal so that in the event of an explosion itwill readily rupture. I

The discharge end of the Ydrying cylinder may have .a dis-charge chute jprovided with rotary feed blades 7c for delivering the nitrocellulosewithout permitting escape of the warm air used for drying, into a funnelm opening into the top of a tank o. Within the funnel m is a powerdriven cork screw-like device n.

The tank o is maintained full of ether, whicheXtends upvin'to the funnelm and also into an overflow device p. Within the tank is a rotaryagitator g.

'lhe device n causes the dry nitrocellulose to mix with the ether.During the feeding and drying operation the agitator g remainsstationary.- Thus the nitrocellulose settles to the bottom,and.the pureether displaced by Ithe nitrocellulose escapes from the tank by way ofthe overflow p.

After the tank o has received the maximumdesigned amount ofnitrocellulose, the feeding mechanism is stopped and the `agitator gstarted so as to thoroughlymechani cally mix the nitrocellulose andether, it beingl understood that the nitrocellulose 'is not soluble inether alone.

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Communicating with the bottom of tank o is a tank s, communicationbetween the tanks being controlled by a plug valve fr. The tank s issimlilar in construction to the tank o, but is-unprovided with anoverflow. It does have, however, an agitator t, similar to agitator 'yin tank o. tank s is a spout o, controlled by a plug valve Vu,discharging into a. press, the latter comprising a cylinder w having a-pivoted top and a pi-ston x provided with a strainer.

A sample of known volume may be taken from tank s to ascertain theweight of nitrocellulose therein. It is thus possible to use the pressas a. measure to determine a definite weight of nitrocellulose. to acalculated volume the press will deliver a definite Weight ofnitrocellulose wetted with a definite volume of ether.

The cakes formed in the press are then -transferred to any suitalblemixing machine. A mixer constructed on the yprinciple of a bread mixingmachine is preferable, such a machine being shown somewhatdiagrammatically in Fig 2, in which y represents the receptacle and a,a, tW-o 'blades rotating therein' in opposite directions, at differentangular speeds. In this machine the predetermined quantity of alcohol,which should equal one-half the volume of ether contained in the cakereceived from the press, is added gradually. I

In the above description of the apparatusand its `operation the severalsteps of the process have been incidentally described with suiicientdetail to enable the essential features of the processto be clearlyunderstood. It is, however, unnecessary toemploy mechanism of anyparticular construction to carry out the process, but the mecha.-

nism described presents features of decided utility and advantage.

The pressure required to eliminate the excess of ether is substantiallyless than is requiredin the old process hereinbefore mentioned to getrid of the excess of alcohol. The pressure being substantially less,- a.hard mass is not formed and no lumps of unmixed material are containedin the finished product.

While I have referred to ether and alcohol as the liquids which togetherform a solvent forthe nitrocellulose, it will 'be understood In thebottom of By pressure that my invention comprehends the use of otherliquids having respectively equivalent properties.

The drier herein described is the subjectmatter of a separateapplication filed July 18, 1917, Serial No. 181,227.

Having now fully described my invention, what I claim and desire toprotect by Letters Patent is:

1. The process of manufacturing` smokeless powder, whichconsists infirst mixing nitrocellulose with ether, then expelling the excess ofether with pressure, and then mixing the; nitrocellulose with alcohol toform a gelatinous or colloidal mass.

2. The process of mainifacturing smokeless powder, which consists indrying nitrocellulose, mixing it with ether, compressing thenitrocellulose to eliminate the excess of ether, and breaking' up thecompressed nitrocellulose and mixing it with alcohol to gelatinize orcolloidize the nitrocellulose.

3. The process of manufacturing smokeless powder, which consists indrying nitrocellulose, conveying it to a body of ether, agitating theether and nitrocellulose to effect their mixture, pressing successivefractional quantities of the entire mixture to expel therefrom theexcess of ether, and then breaking up the compressed nitrocellulose iand adding alcohol thereto.

4. The process of manufacturing smokeless powder, which consists infeeding the same to a body of ether and 'during said feed-ing drivingoff water by means of hea-t, agitating the ether and nitrocellulose toeffect their mixture, pressing successive fractional quantities of themixture to expel therefrom the excess of ether, and then breaking up thepressed cakes and mixing therewith alcohol. y

5. The process of manufacturing smokeless powder, which consists infirst drying nitrocellulose, then immersing the same in a body of etherand mechanically mixing it therewith, then compressing thenitrocellulose to expel the excess of ether, and then mixing withalcohol the nitrocellulose which has been thus wetted with ether.

I n testimony of which invention, I have hereunto set my hand, atPhiladelphia, on this 27th day of April, 1916.

FRANCIS I. DU PONT.

